1. Field of the Invention
The present invention relates to a base station apparatus, ID control apparatus and ID assignment method used in a digital radio communication system.
2. Description of the Related Art
In a digital radio communication system including a plurality of base station apparatuses (hereinafter simply referred to as xe2x80x9cbase stationsxe2x80x9d) that carry out a radio communication with at least one communication terminal apparatus, communication network identification is performed. This communication network identification is performed in the following cases:
(1) To check whether a network is connectable or not prior to authentication, etc. before starting a communication with a base station (AP) (at the time of so-called association) after power to the communication terminal is turned on
(2) To verify a provider of new connection and services supported during handover
Communication network identification is performed using a network ID (hereinafter referred to as xe2x80x9cNET-IDxe2x80x9d). For this NET-ID, several bits of BCCH (Broadcast Control CHannel) are used. Communication networks are identifiable by assigning this NET-ID to each communication network.
Generally, 10 bits of BCCH are used for a NET-ID, making a total of 1024 types of communication network identifiable. This NET-ID is determined when a communication network is installed using random numbers.
Determining a NET-ID using random numbers has an advantage that the NET-ID can be used immediately after a base station is installed and is a NET-ID determination method suited to base stations used for a household network or a small-scale office in-house LAN network.
However, determining a NET-ID using random numbers involves a risk that NET-IDs of adjacent networks will collide with each other. The problem when NET-IDs collide is that communication terminal apparatuses in such a network area can no longer identify the network and cause interference.
It is an object of the present invention to provide a base station apparatus, ID control apparatus and ID assignment method capable of preventing NET-IDs of adjacent networks from colliding with each other.
The present invention attains the above object by carrying out concentrated control over network IDs through an ID control apparatus and assigning network IDs to base station apparatuses.